Pedicle-based intradiscal fixation devices and methods

ABSTRACT

Pedicle-based intradiscal fixation devices, systems, instruments, and methods thereof. The implant or a portion thereof may be composed of a shape-memory material, which has a curved shape-memory orientation and a temporarily straight orientation. The implant may be configured to be inserted into a pedicle of an inferior vertebra, through the vertebral body of the inferior vertebra, and into the vertebral body of the superior vertebra to thereby stabilize the inferior and superior vertebrae.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 16/842,285, Apr. 7, 2020, which is incorporated by referenceherein in its entirety for all purposes.

FIELD OF THE INVENTION

The present disclosure relates to surgical devices, and moreparticularly, to pedicle-based intradiscal fixation devices andassociated methods.

BACKGROUND OF THE INVENTION

Common procedures for handling pain associated with intervertebral discsthat have become degenerated due to various factors such as trauma oraging may include the use of pedicle screw fixation and/orintervertebral fusion for fusing one or more adjacent vertebral bodies.Generally, bilateral pedicle screw fixation, for example, with a rodconstruct, may be used to treat degenerative disc disease and amultitude of other spine pathologies as a standard of treatment tostabilize two or more adjacent vertebral bodies, for example, as anadjunct to spinal fusion.

Unfortunately, a number of iatrogenic pathologies are associated withpedicle screw fixation including, but not limited to, misplacement ofscrews, muscle/ligamentous disruption during insertion, adjacent segmentdisease due to superior adjacent facet violation by the inferior pediclescrew construct, increased procedural time, and/or instrumentationfailure. There exists a clinical need for a fixation system and methodthat reduces the iatrogenic effects of a bilateral pedicle screwconstruct from a posterior approach while stabilizing two adjacentvertebral bodies that may be used as an adjunct to spinal fusion.

SUMMARY OF THE INVENTION

In accordance with the application, pedicle-based devices, systems, andmethods are provided. In particular, pedicle-based intradiscal fixationdevices are provided, which may be used as a standalone device or may beused in conjunction with a traditional interbody fixation device. Themethod of fixation may include inserting the device through the pedicleof an inferior vertebra, into the vertebral body of the inferiorvertebra and securing the device to the vertebral body of the adjacentsuperior vertebra. The pedicle-based intradiscal fixation devices andmethods described herein may improve access-related morbidity whileproviding sufficient stabilization force for spinal fusion.

According to one embodiment, an implant for stabilizing an inferiorvertebra and a superior vertebra includes a first member and a secondmember connected to the first member. The implant has a first, initialinsertion orientation and a second, final implantation orientationdifferent from the first, initial insertion orientation. The firstmember is configured to be inserted through a pedicle of the inferiorvertebra and the second member is configured to engage bone of thesuperior vertebra in the second, final implantation orientation.

According to another embodiment, methods of intradiscal fixation areprovided. A method for stabilizing an inferior vertebra and a superiorvertebra may include: posteriorly accessing a spine of a patient;inserting an implant having a first member and a second member into apedicle of the inferior vertebra in a first, initial orientation;inserting the first member of the implant into a vertebral body of theinferior vertebra; and modifying the implant into a second, finalimplantation orientation and inserting the second member of the implantinto a vertebral body of the superior vertebra, wherein the implanttraverses a disc or disc space between the inferior and superiorvertebrae, and the second, final implantation orientation therebyfixates the inferior and superior vertebrae.

According to one embodiment, the implant may include a pedicle screw, ahousing affixed to the pedicle screw, and an anchor moveably connectedto the housing. The implant has a collapsed position whereby the anchoris positioned close to the pedicle screw, and the implant has anextended position whereby the anchor is moved away from or extended fromthe pedicle screw. The pedicle screw is configured to be insertedthrough a pedicle of the inferior vertebra in the collapsed position,and the anchor is configured to engage bone of the superior vertebra inthe extended position.

The pedicle screw implant may include one or more of the of thefollowing features. The pedicle screw may have a proximal end includinga recess configured to receive an instrument for inserting the pediclescrew and a distal end configured to be inserted into the pedicle of theinferior vertebra. The pedicle screw may include one or more threadsconfigured to engage bone. The housing may include a first portionconfigured to receive the pedicle screw and a second portion configuredto retain the anchor therein. The anchor may be configured to move,pivot, or articulate relative to the pedicle screw. The anchor may havea proximal end configured to be received in the housing and a distal endconfigured to be inserted into a vertebral body of the superior vertebrain the extended position. The anchor may be curved between the proximaland distal ends. The anchor may be generally positioned perpendicular tothe pedicle screw in the extended position. The anchor may include oneor more tracks configured to engage corresponding tracks within thesecond portion of the housing, and thereby allow for movement of theanchor between the collapsed and extended positions.

According to another embodiment, the implant may include a curved outertube and a curved inner tube positionable within the outer tube. Theimplant has a collapsed position whereby the inner tube is positionedinside the outer tube, and the implant has an extended position wherebythe inner tube extends from the outer tube. The outer tube is configuredto be inserted through a pedicle of the inferior vertebra in thecollapsed position, and the inner tube is configured to engage bone ofthe superior vertebra in the extended position.

The tube implant may include one or more of the of the followingfeatures. The inner tube may include one or more ribs extending alongthe length of the tube configured to engage bone. The outer and innertubes may be hollow and may be configured to receive bone cementtherethrough. The implant may further include a separate segmented tubeconfigured to advance the inner tube and stabilize the outer tube. Thesegmented tube may include a plurality of articulating links. Each ofthe links may include a joint, such as a ball and a socket configured toreceive the ball of an adjacent link. The segmented tube may beencapsulated by the outer tube in the extended position.

According to another embodiment, the implant may include a screw portionand an anchor portion moveably coupled to the screw portion. The implanthas a collapsed position whereby the anchor portion is positionedsubstantially in line with the screw portion, and the implant has anextended position whereby the anchor portion is extended away from thescrew portion. The screw portion is configured to be inserted through apedicle of the inferior vertebra in the collapsed position, and theanchor portion is configured to engage bone of the superior vertebra inthe extended position.

The anchor implant may include one or more of the of the followingfeatures. The implant may further include a rod portion receivable inthe screw portion. The implant may also include a push rod connected toa distal end of the screw portion by a first pin and connected to theanchor portion by a second pin. When the screw portion moves forwardalong the rod portion, the push rod may push forward and slide theanchor portion outward into the extended position. The rod portion mayinclude one or more tracks configured to mate with corresponding tracksalong the anchor portion, thereby facilitating movement of the anchorportion relative to the screw portion.

According to another embodiment, the implant includes a curved nail anda flexible screw moveable along the length of the nail. The implant hasa first position whereby the nail is configured to be inserted into apedicle of the inferior vertebra, a vertebral body of the inferiorvertebra, and a vertebral body of the superior. The implant has a finalposition whereby the screw is inserted over the nail to rigidly lock thenail and screw together and provide resistance to pullout. The flexiblescrew may include one or more threads, and the flexible screw may havean open helical design with gaps between crests of the one or morethreads.

According to another embodiment, the implant includes a body extendingfrom a proximal end to a distal end, a pivotable head connected to thedistal end of the body, and an actuator for moving the pivotable headbetween an inline position and a transverse position. The implant isconfigured to be inserted through a pedicle of the inferior vertebra andinto the superior vertebra. The body may be made of a shape-memorymaterial such that the body has a curved shape-memory orientation and atemporarily straight orientation. The body may include a first half anda second half. The first and second halves may be permitted to slideindependent of one another. The first half may include one or more maleportions and the second half may include one or more female portionsconfigured to receive the one or more male portions of the first half.The male portion may include a first set of two opposed projectionsextending away from one another and configured to fit within a first setof two corresponding opposed recesses in the second half, and the secondhalf may include a second set of two opposed projections extendingtoward one another and configured to fit within a second set of twocorresponding opposed recesses within the male portion of the firsthalf. The actuator may be a set screw or other suitable actuationmechanism. When the actuator presses against the first half of the body,the opposite end of the first half may in turn push on the pivotablehead, thereby causing the head to pivot. Once the head fully pivots intothe transverse position, the actuator may be configured to preventmovement of the first and second halves relative to each other, therebycausing the body to increase in stiffness.

According to yet another embodiment, a method for stabilizing aninferior vertebra and a superior vertebra may include one or more of thefollowing steps: (1) posteriorly accessing a spine of a patient; (2)inserting an implant having a body having a first half and a second halfslidable relative to one another, a pivotable head connected to thebody, and an actuator configured to move the pivotable head into apedicle of the inferior vertebra with the pivotable head in an inlineorientation; (3) inserting the implant into a vertebral body of theinferior vertebra; (4) inserting the implant into a vertebral body ofthe superior vertebra, wherein the implant traverses a disc or discspace between the inferior and superior vertebrae; and (5) moving thepivotable head to a transverse orientation, thereby fixating theinferior and superior vertebrae. The body may be composed of ashape-memory material. The method may further include drawing theimplant into a straight deployment tube such that the body isstraightened within the tube, and deploying the implant from thedeployment tube such that the body returns to a curved shape. The methodmay also include moving the pivotable head by actuating the actuatorsuch that the actuator presses against the first half of the body andthe first half in turn pushes on the pivotable head, thereby causing thehead to pivot. Once the head fully pivots into the transverseorientation, the actuator may be configured to prevent movement of thefirst and second halves relative to each other, thereby causing the bodyto increase in stiffness.

According to another embodiment, the implant includes an inner coreextending from a proximal end to a distal end, an outer segmented sheathpositioned over the inner core, and a nut configured to compress theouter segmented sheath. The implant is configured to be inserted througha pedicle of the inferior vertebra and into the superior vertebra. Theinner core may be made of a shape-memory material, and the inner coremay have a curved shape-memory orientation and a temporarily straightorientation. The segmented sheath may include a plurality of links. Theplurality of links may be configured to be arranged in a generallylinear configuration or a curved configuration to mimic the shape of theinner core. The implant may include a proximal end cap and/or a distalend cap to prevent disassembly of the outer sheath from the inner core.The proximal end cap, if present, may include a plurality of outerthreads configured to retain the nut. When the nut is moved forwarddistally and abuts the segmented sheath, the segmented sheath may betightened between the nut and the distal end cap, thereby locking theouter segmented sheath.

Also provided are kits including pedicle-based intradiscal fixationdevices of varying types and sizes, interbody fusion devices of varyingtypes and sizes, rods, fasteners or anchors, k-wires, insertion tools,and other components for performing the procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, wherein:

FIG. 1 is a lateral view of two adjacent vertebrae with a pedicle-basedintradiscal fixation device implanted through the pedicle of theinferior vertebra and engaged with the vertebral body of the superiorvertebra according to one embodiment;

FIG. 2 is a posterior view of the vertebrae and pedicle-basedintradiscal fixation device of FIG. 1;

FIG. 3 is a perspective view of the pedicle-based intradiscal fixationdevice of FIG. 1;

FIG. 4 is a side view of the pedicle-based intradiscal fixation deviceof FIG. 3 in a collapsed position;

FIG. 5 is a side view of the pedicle-based intradiscal fixation deviceof FIG. 3 in an extended position;

FIG. 6 is a lateral view of two adjacent vertebrae with a pedicle-basedintradiscal fixation device in a collapsed position implanted throughthe pedicle of the inferior vertebra according to one embodiment;

FIG. 7 is a lateral view of two adjacent vertebrae and the pedicle-basedintradiscal fixation device of FIG. 6 with the device in an extendedposition and further implanted into the vertebral body of the superiorvertebra;

FIG. 8 is a perspective view of the pedicle-based intradiscal fixationdevice of FIG. 6 in a collapsed position;

FIG. 9 is a perspective view of the pedicle-based intradiscal fixationdevice of FIG. 8 in an extended position;

FIG. 10 is an exploded perspective view of a pedicle-based intradiscalfixation device according to another embodiment with the device in acollapsed position and a separate segmented device;

FIG. 11 is the pedicle-based intradiscal fixation device of FIG. 10 withthe segmented device inserted into the outer tube to advance the innermember to the extended position;

FIG. 12 is a close-up view of the segmented device with a plurality oflinks in a linear configuration;

FIG. 13 is a close-up view of the segmented device with a plurality oflinks in a curved configuration;

FIGS. 14A-14B are close-up views of a segmented device according to oneembodiment;

FIGS. 15A-15B are close-up views of a segmented device according toanother embodiment;

FIGS. 16A-16B are close-up view of a segmented device according to yetanother embodiment;

FIG. 17 is a lateral view of two adjacent vertebrae with a pedicle-basedintradiscal fixation device implanted through the pedicle of theinferior vertebra and engaged with the vertebral body of the superiorvertebra according to one embodiment;

FIG. 18 is a posterior view of the vertebrae and pedicle-basedintradiscal fixation device of FIG. 17;

FIG. 19 is a perspective view of the pedicle-based intradiscal fixationdevice of FIG. 17 in an extended position;

FIG. 20 is a side view of the pedicle-based intradiscal fixation deviceof FIG. 19 in the extended position;

FIG. 21 is a side view of pedicle-based intradiscal fixation device ofFIG. 19 in a collapsed position with a mechanism for extending theanchor portion;

FIG. 22 is a side view of the pedicle-based intradiscal fixation deviceof FIG. 21 in an extended position with the mechanism extending theanchor portion;

FIGS. 23A-23D provide lateral and posterior views, respectively, of twoadjacent vertebrae with a pedicle-based intradiscal fixation deviceimplanted through the pedicle of the inferior vertebra and engaged withthe vertebral body of the superior vertebra according to one embodiment;

FIG. 24 is a perspective view of the pedicle-based intradiscal fixationdevice of FIGS. 23A-23D with the device in an initial position;

FIG. 25 is a perspective view of the pedicle-based intradiscal fixationdevice of FIG. 24 with the device in a final, installed position;

FIGS. 26A-26E provide alternative views of the flexible screw of FIG.25;

FIGS. 27A-27D provide alternative views of a flexible screw according toone embodiment;

FIGS. 28A-28H provide alternative views of a flexible screw according toanother embodiment;

FIGS. 29A-29E provide alternative views of a flexible screw according toyet another embodiment;

FIGS. 30A-30C provide views of two adjacent vertebrae with apedicle-based intradiscal fixation device implanted through the pedicleof the inferior vertebra and engaged with the vertebral body of thesuperior vertebra according to another embodiment;

FIG. 31 is a perspective view of the pedicle-based intradiscal fixationdevice of FIGS. 30A-30C;

FIG. 32 is a cross-sectional view of the pedicle-based intradiscalfixation device of FIG. 31;

FIGS. 33A-33D depict side and cross-sectional views, respectively, ofthe pedicle-based intradiscal fixation device of FIG. 31 with thepivotable head arranged in inline and transverse positions;

FIG. 34 is a perspective view of two adjacent vertebrae with apedicle-based intradiscal fixation device according to anotherembodiment implanted through the pedicle of the inferior vertebra andengaged with the vertebral body of the superior vertebra;

FIG. 35 is a perspective view of the pedicle-based intradiscal fixationdevice of FIG. 34;

FIGS. 36A-36D depict side and cross-sectional views, respectively, ofthe pedicle-based intradiscal fixation device of FIG. 35 in open andlocked configurations;

FIG. 37 is a perspective view of two adjacent vertebrae with apedicle-based intradiscal fixation device according to anotherembodiment implanted through the pedicle of the inferior vertebra andengaged with the vertebral body of the superior vertebra; and

FIG. 38 is a perspective view of the pedicle-based intradiscal fixationdevice of FIG. 37.

DETAILED DESCRIPTION OF THE INVENTION

Bilateral pedicle screw fixation has been used to treat degenerativedisc disease and other spine pathologies. However, a number ofiatrogenic pathologies are associated with pedicle screw fixation. Thus,there is a need for a fixation method that reduces the iatrogeniceffects of a bilateral pedicle screw construct from a posterior approachwhile stabilizing the two adjacent vertebral bodies. According to oneembodiment, an inferior pedicle-based intradiscal fixation method may beused in a standalone method or in conjunction with a traditionalinterbody fixation device. The system may improve access-relatedmorbidity while providing sufficient stabilization force for spinalfusion. Accordingly, embodiments of the present application aregenerally directed to devices, systems, and methods for pedicle-basedintradiscal fixation of two adjacent vertebrae. The terms device,fixation device, and implant may be used interchangeably herein.

Referring now to FIGS. 1 and 2, a pedicle-based intradiscal fixationdevice 20 according to one embodiment is shown implanted into twoadjacent vertebrae 2, namely, a superior vertebra 4 and an inferiorvertebra 6. The method of fixation may include, for example, accessingthe spine from the posterior and inserting the device 20 into thepedicle 8 of the inferior vertebra 6. If necessary, bone may be removedfrom the inferior pedicle 8 and/or the vertebral body 12 in order tofacilitate placement of the device 20. The device 20 may be furtheradvanced into the vertebral body 12 of the inferior vertebra 6. Asshown, the device 20 may be angled or directed toward the superior ofthe inferior body 6, but it is also envisioned that the location andorientation of the device 20 may be selected by a surgeon. The device 20may be configured to be inserted and secured to the vertebral body 10 ofthe adjacent superior vertebra 4. Thus, the device 20 may traverse thedisc and/or disc space 14 between the two vertebrae 2. In this manner,the device 20 may be configured to be implanted into both vertebrae 2from a posterior approach, thereby allowing for fusion of the adjacentvertebrae 2. One or more pedicle-based devices 20 may be used alone orin conjunction with a traditional interbody fusion device. Although themethod is shown with respect to a single inferior pedicle 8, it will beappreciated that the other inferior pedicle (not shown) may also receivethe same or a similar device. It will also be appreciated that the sameor similar devices may also be used on adjacent or other levels.

Turning now to FIGS. 3-5, the pedicle-based intradiscal fixation device20 is shown in more detail. The pedicle-based implant 20 may include apedicle screw 22, a housing 24 affixed to the pedicle screw 22, and ananchor 26 moveably connected to the housing 24. As best seen in FIG. 4,the implant 20 has a collapsed configuration whereby the anchor 26 ispositioned close to the pedicle screw 22, thereby allowing the implant20 to be inserted into the pedicle 8 of the inferior vertebra 6, forexample, in a minimally invasive manner. As shown in FIG. 5, onceinserted in the inferior vertebra 6, the implant 20 has an expanded orextended configuration whereby the anchor 26 is moved away from thepedicle screw 22, thereby allowing for the anchor 26 to be inserted intothe superior vertebra 4.

The pedicle screw 22 may have a body extending from a first end 30 to asecond 32. The first end 30 may be a proximal end and may include arecess 34 configured to receive an instrument for inserting the pediclescrew 22. The first end 30 may have an enlarged head portion or may beotherwise configured (e.g., headless). The second end 32 may be a distalend configured to be inserted into the pedicle 8 of the inferiorvertebra 6. The second end 32 may have a distal tip that is blunt,pointed, or otherwise configured to engage bone. The body of the pediclescrew 22 may include one or more threads 36 along the entire length ofthe shaft or a portion thereof. The thread 36 may have a suitable angle,lead, pitch, etc. to enhance insertion and/or engagement with the bone.Although a pedicle screw 22 is exemplified in this embodiment, it willbe appreciated that the pedicle screw 22 could be substituted with abone anchor, nail, or other fixation device.

The housing 24 may be affixed to the pedicle screw 22. The housing 24may include a first portion 40 configured to receive the pedicle screw22. For example, the first portion 40 may have an opening extendingtherethrough configured to receive the shaft of the pedicle screw 22 ina position where the threads 36 are absent. The outer surface of thefirst portion 40 may be dimensioned to be smaller than the majordiameter of the threads 36. The housing 24 may be positioned centrallyalong the pedicle screw 22 or more towards the distal end 32. Thehousing 24 may include a second portion 42 configured to retain theanchor 26. The second portion 42 may include an opening configured toreceive the anchor 26, which is configured to move, slide, pivot, orarticulate the anchor 26 relative to the screw 22.

The anchor 26 may have a body extending from a first end 50 to a secondend 52. The first end 50 may be a proximal end and the second end 52 maybe a distal end configured to be inserted into the vertebral body 10 ofthe superior vertebra 4. The second end 52 may have a distal tip that issharp, pointed, or otherwise configured to engage bone. The body of theanchor 26 may include one or more tracks 54 configured to engagecorresponding tracks within the opening of the second portion 42 of thehousing 24. The one more mating tracks 54 may be provided to allow formovement of the anchor 26 between the collapsed and extended positions.For example, in the collapsed position, shown in FIG. 4, the distal end52 of the anchor 26 may be received in the housing 24, and after a forceis applied to the proximal end 50 of the anchor 26, the anchor 26 movesinto the extended position, shown in FIG. 5, such that the proximal end50 of the anchor 26 is received in the housing 24. In the extendedposition, the anchor 26 may be generally positioned perpendicular to thepedicle screw 22 or the anchor 26 may be angled or otherwise oriented toengage the vertebral body 10 of the superior vertebra 4. It is alsoenvisioned that the anchor 26 could pivot in the housing 24 about ajoint, such as a pin joint or hinge joint. Although a single anchor 26is depicted in this embodiment, it will be appreciated that additionalanchors 26 could be received in the housing 24. Multiple anchorgeometries may be used to facilitate stability, for example, one or moreanchors 26 may be inserted into the anchor housing 24 with orientationvariances in up to three planes.

Referring now to FIGS. 6 and 7, a pedicle-based intradiscal fixationdevice 60 according to another embodiment is shown. In FIG. 6, thepedicle-based implant 60 is implanted into the inferior vertebra 6 in acollapsed position. In FIG. 7, the pedicle-based implant is deployed toan expanded or extended position such that the implant 60 is implantedinto the vertebral body 10 of the superior vertebra 4. The method offixation may be similar to the method described for device 20. Forexample, the spine may be accessed posteriorly and the device 60 may beinserted into the pedicle 8 of the inferior vertebra 6. If necessary,bone may be removed from the inferior pedicle 8 and/or the vertebralbody 12 in order to facilitate placement of the device 60. The device 60may be further advanced into the vertebral body 12 of the inferiorvertebra 6. The device 60 may be configured to be inserted and securedto the vertebral body 10 of the adjacent superior vertebra 4. Thus, thedevice 60 may traverse the disc and/or disc space 14 between the twovertebrae 2. If desired, cement may be injected through the implant 60to rigidly fixate the implant 60 to the superior vertebral body 10.

Turning now to FIGS. 8 and 9, the pedicle-based intradiscal fixationdevice 60 is shown in more detail. The pedicle-based implant 60 mayinclude two or more concentric tubes. In particular, the implant 60 mayinclude a first tube or outer tube 62 and a second tube or inner tube 64positionable within the outer tube 62. As best seen in FIG. 8, theimplant 60 has a collapsed configuration whereby the inner tube 64 ispositioned inside the outer tube 62, thereby allowing the implant 60 tobe inserted into the pedicle 8 of the inferior vertebra 6, for example,in a minimally invasive manner. As shown in FIG. 9, once inserted in theinferior vertebra 6, the implant 60 has an expanded or extendedconfiguration whereby the inner tube 64 extends from the outer tube 62,thereby allowing for the inner tube 64 to be inserted into the superiorvertebra 4.

The first tube or outer tube 62 may have a body extending from a firstend 66 to a second end 68. The first end 66 may be a proximal end andthe second end 68 may be a distal end configured to be inserted into thepedicle 8 of the inferior vertebra 6. The outer tube 62 may be generallyhollow and may be curved along its length. The second tube or inner tube64 may have a body extending from a first end 70 to a second end 72. Thefirst end 70 may be a proximal end and the second end 72 may be a distalend configured to be inserted into the vertebral body 10 of the superiorvertebra 4. The second end 72 may have a distal tip that is blunt,sharp, or otherwise configured to engage bone. The second tube 64 mayalso have one or more ribs 74 extending along the length or a portionthereof of the tube 64 configured to engage bone. The inner tube 64 maybe generally hollow and may be curved along its length. In analternative embodiment, the inner tube 64 may be an anchor, keel, orother fixation device and is not necessarily hollow throughout.

In one embodiment, the implant 60 may be installed as follows. Theconcentric curved tubes 62, 64 may be inserted into the pedicle 8 of theinferior vertebra 6. An instrument drives the inner concentric tube 64into the superior vertebral body 10. Bone cement, such as polymethylmethacrylate (PMMA) or a suitable self-setting orthopedic cementcomposition, may be injected through the concentric curved tubes 62, 64to rigidly fixate the implant assembly to the superior vertebral body10. In addition or in the alternative, bone cement may be insertedthrough the superior vertebral body pedicle to rigidly fixate theimplant assembly to the superior vertebral body 10.

Referring now to FIGS. 10 and 11, a pedicle-based intradiscal fixationdevice 80 according to another embodiment is shown. The concentriccurved tubes 62, 64 may be the same as described for implant 60 with aseparate segmented tube 82 configured to advance the inner tube 64 andstabilize the outer tube 62. The segmented tube 82 may include aplurality of articulating members or links 84 that act like puzzlepieces. The plurality of links 84 may be arranged in a generally linearconfiguration, as shown in FIG. 12, or may be curved, as shown in FIG.13, for example, to mimic the shape of the outer tube 62.

As best seen in FIGS. 12 and 13, each link 84 extends from a first end86 to a second end 88. In this case, either the first end 86 or thesecond end 88 of a first link 84 may be inserted into the outer tube 62.In the embodiment shown, eight links 84 are connected such that thesecond end 88 of a given link 84 connects to the first end 86 of thenext link 84 in the chain. Although it will be appreciated that anynumber of links 84 may be selected. Each of the links 84 are connectedand able to articulate about a joint 90. In this embodiment, the firstend 86 of each link 84 includes a ball 92 and the second end 88 of eachlink 84 includes a socket 94 configured to receive the ball 92 of anadjacent link 84. Accordingly, the socket 94 in the second end 88 of agiven link 84 connects to the ball 92 of the first end 86 of the nextlink 84 in the chain. In this manner, each link 84 is able to articulaterelative to the next link 84, thereby forming a curved segmented tube82. Although a ball and socket joint 90 is exemplified in thisembodiment, it will be appreciated that other suitable joints could beselected, such as pin joints, pivot joints, hinge joints or the like. Itwill also be appreciated that the locations of the ball 92 and socket 94could be reversed on each link 84 or otherwise configured.

In one embodiment, the implant 80 may be installed as follows. Theconcentric curved tubes 62, 64 may be inserted into the pedicle 8 of theinferior vertebra 6. The articulatable puzzle pieces or links 84 of thesegmented tube 82 may be impacted, for example, through a straightinstrument connected to the proximal end 66 of the concentric tubes 62,64. For example, the straight links 84 may be impacted one by one intothe outer curved tube 62. The links 84 articulate and lock into a curvedorientation during impaction. As additional links 84 are impacted, theinner tube 64 is incrementally advanced past the distal end 68 of theouter curved tube 62 and into the superior vertebral body 10. Thus, thesegmented tube 82 drives the inner concentric tube 64 into the superiorvertebral body 10. The segmented tube 82 may be configured to beencapsulated in the outer curved tube 62, thereby adding rigidity to theouter tube 62. If desired, bone cement may be injected through theconcentric curved tubes 62, 64 and/or separately added to the superiorvertebra 4 as described previously. In an alternative embodiment, ifcement is not needed to be dispensed through the device 80, thesegmented tube 82 may be solid and does not need to be hollowthroughout.

Turning to FIGS. 14A-16B, alternative locking geometries may be used forthe links 84, for example, to improve rigidity of the final construct.It will be appreciated that all of the links 84 for a given segment areshown identical, but it is envisioned that different links could beprovided through the chain. In one embodiment shown in FIGS. 14A-14B,the second end 88 of the link 84 includes a protrusion or tab 96configured to engage a corresponding recess 98 in an adjacent link 84.The tab 96 may be positioned, for example, below the socket 94 of thelink 84 and the recess 98 may be positioned below the ball 92. In thestraight configuration shown in FIG. 14A, the tabs 96 are not engagedwith the recesses 98. In the curved configuration shown in FIG. 14B, thetabs 96 are locked in the respective recesses 98 of the adjacent links84. In the embodiment shown in FIGS. 15A-15B, in addition to tab 96, abump 100 is positioned above the recess 98 and an additional protrusionor spike 102 is provided. The bump 100 may be received in acorresponding recess 104 positioned adjacent to the tab 96, therebyfurther securing adjacent links 84 together. An upper portion of thesecond end 88 above the socket 94 may include a protrusion or spike 102,which is receivable in one or more corresponding notches 106 in the bodyof an adjacent link 84. In this manner, the spike 102 may act as aratchet as it moves through one or more notches 106 as the links 84articulate. In the curved configuration shown in FIG. 15B, the spike 102may engage with a corresponding protrusion or spike 108 between two ormore notches 106. In the embodiment shown in FIGS. 16A-16B, in additionto the features in FIGS. 15A-15B, the upper portion above the socket 94may further includes a curved protrusion 110 adjacent to spike 100,which may be configured to further lock the link 84 to an adjacent link84. For example, the protrusion 110 may be received in one of thenotches 106 in the body of an adjacent link 184. One or more of thelocking geometries may be used for one or more of the links 84, forexample, to improve rigidity of the segmented tube 82.

Turning now to FIGS. 17 and 18, a pedicle-based intradiscal fixationdevice 120 according to another embodiment is shown. The method offixation may be similar to the methods described herein for otherdevices. For example, the spine may be accessed posteriorly and thedevice 120 may be inserted into the pedicle 8 of the inferior vertebra 6in a collapsed configuration. The device 120 may be further advancedinto the vertebral body 12 of the inferior vertebra 6. The device 120may then be expanded or extended into the vertebral body 10 of theadjacent superior vertebra 4. Thus, the device 120 may traverse the discand/or disc space 14 between the two vertebrae 2.

Referring to FIGS. 19-22, the pedicle-based intradiscal fixation device120 is shown in more detail. The pedicle-based implant 120 may include ascrew portion 122 and an anchor portion 126 moveably connected to thescrew portion 122. As best seen in FIG. 21, the implant 120 has acollapsed configuration, thereby allowing the implant 120 to be insertedinto the pedicle 8 of the inferior vertebra 6, for example, in aminimally invasive manner. As shown in FIG. 22, once inserted in theinferior vertebra 6, the implant 120 has an expanded or extendedconfiguration whereby the anchor portion 126 is extended outwardly,thereby allowing for the anchor portion 126 to be inserted into thesuperior vertebra 4.

The screw portion 122 may have a body extending from a first end 130 toa second 132. The first end 130 may be a proximal end and may include arecess 134 configured to receive an instrument for inserting the implant120. The first end 130 may have an enlarged head portion or may beotherwise configured (e.g., headless). The second end 132 may be adistal end coupled to the moveable anchor portion 126. The screw portion122 may be generally hollow and may be configured to slide along a rodportion 124. The body of the pedicle screw 122 may include one or morethreads 136 along the entire length of the shaft or a portion thereof.The thread 136 may have a suitable angle, lead, pitch, etc. to enhanceinsertion and/or engagement with the bone. Although a threaded screwportion 122 is exemplified in this embodiment, it will be appreciatedthat it could be substituted with ribs, teeth, or other bone fixationmechanisms.

The anchor portion 126 may have a body extending from a first end 150 toa second end 152. The first end 150 may be a proximal end and the secondend 152 may be a distal end configured to be inserted into the vertebralbody 10 of the superior vertebra 4. The second end 152 may have a distaltip that is sharp, pointed, or otherwise configured to engage bone. Theanchor portion 126 may be curved or otherwise contoured. The anchorportion 126 may have sufficient length such that the anchor 126 may spanfrom the inferior vertebra 6 to the superior vertebra 4 through theaffected disc space 14. In the extended position, the anchor portion 126may be generally positioned perpendicular to the screw portion 122 orthe anchor portion 126 may be angled or otherwise oriented to engage thevertebral body 10 of the superior vertebra 4.

As best shown in FIGS. 21 and 22, an articulation assembly 140 isconfigured to articulate the anchor portion 126 from the collapsedposition to the extended position. The articulation assembly 140 mayinclude a push rod 142 connected to the distal end 132 of the screwportion 122 by a first pin 144 and connected to the anchor portion 126by a second pin 146. When the screw portion 122 moves forward along therod portion 124, the push rod 142 pushes forward and slides the anchorportion 142 outward. The anchor portion 142 and rod portion 124 mayinclude one or more corresponding tracks configured to facilitate themovement. An instrument 154 may be provided to articulate the anchorportion 142. For example, as shown in FIG. 21, the instrument 154 may beaffixed to the head of the screw portion 122. An inner rod 156 of theinstrument 154 may be inserted through the screw portion 122 and maycouple to the rod portion 124 of the implant 120. When the screw portion122 is moved forward along the inner rod 156 and the rod portion 124and/or the inner rod 156 is withdrawn from the screw portion 122, theanchor portion 126 articulates outward into the extended position shownin FIG. 22. Once in its final extended position, one or more lockingmembers may be used to lock the articulated implant 120, therebyfacilitating resistance to toggle. For example, a threaded locking cap158 may be inserted into the recess 134 of the implant 120 to lock theanchor portion 126 in the extended position.

Turning now to FIGS. 23A-23D, a pedicle-based intradiscal fixationdevice 160 according to another embodiment is shown. The method offixation may be similar to the methods described herein for otherdevices. For example, the spine may be accessed posteriorly and thedevice 160 may be inserted into the pedicle 8 of the inferior vertebra 6in a first or initial configuration, shown in FIG. 23A. The device 160may be further advanced into the vertebral body 12 of the inferiorvertebra 6 and into the vertebral body 10 of the adjacent superiorvertebra 4. Thus, the device 160 may traverse the disc and/or disc space14 between the two vertebrae 2. The device 160 may be manipulated into asecond or final configuration by positioning a flexible screw 164 over acurved nail 162, as shown in FIG. 23C.

Referring to FIGS. 24 and 25, the pedicle-based intradiscal fixationdevice 160 is shown in more detail. The pedicle-based implant 160 mayinclude a nail 162 and a screw 164 moveable along the length of the nail162. As best seen in FIG. 24, the implant 160 has an initialconfiguration, whereby the nail 162 may be inserted into the pedicle 8of the inferior vertebra 6, the vertebral body 12 of the inferiorvertebra 6, and the vertebral body 10 of the superior vertebra 4. Asshown in FIG. 25, the implant 160 has a final configuration whereby thescrew 164 is inserted over the nail 162 to rigidly lock the segments andprovide resistance to pullout.

The nail 162 may have a body extending from a first end 166 to a secondend 168. The first end 166 may be a proximal end and the second end 168may be a distal end configured to be inserted into the vertebral body 10of the superior vertebra 4. The second end 168 may have a distal tipthat is sharp, pointed, or otherwise configured to engage bone. The nail162 may have one or more helical channels or grooves 170 configured toengage bone and/or facilitate movement of the screw 164 when insertedover the nail 162. In other words, the nail 162 may be threaded alongits entire length or a portion thereof. The nail 162 may be curved orotherwise contoured along its length. For example, the nail 162 may havea first straight portion near the proximal end 166, a curved portion,and then a second straight portion near the distal end 168. The nail 162may be sufficiently rigid such that it maintains its shape as the screw164 is inserted thereon. The nail 162 may have a sufficient length suchthat nail 162 may span from the pedicle 8 to the inferior vertebra 6 andto the superior vertebra 4 through the affected disc space 14.

Alternative versions of the screw 164 are shown in FIGS. 26-29. Thescrew 164 may have a body extending from a first end 172 to a second174. The first end 172 may be a proximal end and may include a recess176 configured to receive an instrument for inserting the screw 164. Asbest seen in FIGS. 26A-26D, the first end 172 may have an enlarged headportion 180. Alternatively, as shown in FIGS. 27A-27D, the first end 172may be headless. The second end 174 may have a distal tip that is blunt,pointed, or otherwise configured to engage bone. The screw 164 may begenerally hollow and may be configured to receive the nail 162 therein.The screw 164 may be formed by one or more threads 178. The thread 178may be an open helical spring with gaps between each of the crests ofthe thread 178. The thread 178 may have a suitable angle, lead, pitch,etc. to enhance insertion and/or engagement with the bone.

As best seen in FIGS. 28A-28H, the flexible screw 164 may have agenerally linear or straight configuration and may be bent into agenerally curved configuration. Due to the open geometry of the thread178, the screw 164 may be flexible such that it is capable of bendingeasily to conform to the curved geometry of the nail 162. Accordingly,after the threaded curved nail 162 is inserted into the inferior pedicle8 through to the superior vertebral body 10, spanning the intradiscalspace 14, the flexible screw 164 may be threaded over the threadedcurved nail 162 to rigidly lock the segments and provide resistance topullout.

Turning now to FIGS. 30A-30C, a pedicle-based intradiscal fixationdevice or anchor 200 according to another embodiment is shown. Themethod of fixation may be similar to the methods described herein forother devices. For example, the spine may be accessed posteriorly andthe device 200 may be inserted into the pedicle 8 of the inferiorvertebra 6 in a first or inline configuration. The device 200 may befurther advanced into the vertebral body 12 of the inferior vertebra 6.The device 200 may be positioned into the vertebral body 10 of theadjacent superior vertebra 4, and then the head 208 may be extended orarticulated into a second or transverse configuration. Thus, the device200 may be incorporated into the inferior pedicle 8 which allows theanchor 200 to span from inferior to superior vertebrae 4, 6 through theaffected disc space 14.

Referring to FIGS. 31-33, the pedicle-based intradiscal fixation deviceor anchor 200 is shown in more detail. The pedicle-based implant oranchor 200 may include a body 202 extending from a first end or proximalend 204 to a second end or distal end 206, a pivotable head 208connected to the distal end 206 of the body 202, and an actuator 210 formoving the pivotable head 208 between an inline or contracted positionand a transverse or extended position. The body 202 may be composed ofan elastic or flexible material, such as polyetheretherketone (PEEK). Inone embodiment, the body 202 is made of a shape-memory material. Forexample, the body 202 may be composed of a suitable biocompatiblepolymer, metal, alloy, or other suitable material configured to impartshape memory to the body 202 of the implant 200. The body 202 may have agenerally curved or bent shape memory but is also able to be temporarilystraightened or modified into a temporary shape.

In order to deploy the anchor 200, the anchor 200 may be first drawninto a deployment tube 190 (e.g., shown in FIG. 37). When the anchor 200is positioned within a straight deployment tube 190, the anchor 200 isunbent and held in a straight orientation inside the deployment tube190. In other words, the anchor 200 is able to temporarily mimic theshape of the deployment tube 190. The anchor 200 may be able to flexinto a straight orientation due to the elastic properties of thematerial (e.g., PEEK) as well as the cross sectional area of the anchor200. After the anchor 200 is deployed from the deployment tube 190, theimplanted anchor 200 returns to its original curved or bent shape.

The pedicle-based implant or anchor 200 may include a multi-componentbody 202. The body 202 may include a first half, inner half, or upperportion 212 and a second half, outer half, or lower portion 214. Thefirst half 212 and/or second half 214 may include a plurality ofserrations, teeth, or friction enhancing surfaces 222, for example. Theserrations or teeth 222 may extend along the entire length of the firsthalf 212 and/or the second half 212 or a portion thereof. The serrationsor teeth 222 may be configured to grip the bone of the vertebrae 2. Inthe embodiment shown in FIG. 30A, teeth 222 are provided along an uppersurface of the first half 212 and the lower portion 214 has a smoothouter body. The smooth outer body may be configured to ease insertioninto the bone. In the embodiment shown in FIG. 30B, the first and secondhalves 212, 214 each have teeth 222 extending along the outer surfaces,respectively. Although the teeth 222 and smooth surfaces areexemplified, it will be appreciated that other configurations may beused.

As best seen in the cross-section shown in FIG. 32, the first half 212may include one or more male portions 218 and the second half 214 mayinclude a recess with one or more female portions 220 configured toreceive the male portions 218 of the first half 212. For example, themale portion 218 may include a first set of two opposed projections 219extending away from one another and configured to fit within a first setof two corresponding opposed recesses 221 in the second half 214. Inaddition, the second half 214 may include a second set of two opposedprojections 223 extending toward one another and configured to fitwithin a second set of two corresponding opposed recesses 225 within themale portion 218 of the first half 212. In this manner, the two halves212, 214 may be keyed together but are permitted to slide independent ofeach other. Unlike a solid anchor (e.g., a solid PEEK anchor) that wouldbe unable to flex into a straight orientation without plasticallydeforming, the two halves 212, 214 of the anchor 200 are able toelastically flex into a straight orientation without deforming and whenthe anchor 200 is deployed, the anchor 200 is able to resume itsoriginal bent shape.

As best seen in the cross-sectional view of FIG. 32, the body 202 mayinclude a center canal or opening 216, which may be used to send theanchor 200 over a bent guide wire that has already been deployed throughthe pedicle 8 and up into the superior vertebral body 10. Alternatively,or in addition, the canal or opening 216 may be configured to contain acurved piece of Nitinol or other shape memory material in order toincrease the bend rigidity of the construct.

The proximal end 204 of the anchor 200 may include a plurality of outerthreads or an outer threaded portion 224. The outer threaded portion 224may be configured to connect to an insertion instrument, for example.The proximal end 204 may also include a plurality of inner threads or aninner threaded portion 227. The inner threaded portion 227 may beconfigured to receive a threaded actuator 210. The distal end 206 of thebody 202 may connect to the pivoting head 208. For example, the secondhalf 214 may connect to the pivoting head 208 with a pin 226. The anchor200 may include the pivoting head 208 in order to secure the anchor 200into the superior vertebral body 10 after the anchor 200 has beendeployed. The pivoting head 208 may have a tip that is conical, pointed,or otherwise configured to engage bone. As best seen in FIGS. 33A and33B, the pivoting head 208 has a first position or inline orientation,which is generally aligned with the curvature of the body 202 of theanchor 200. When constrained by a straight deployment tube 190, the head208 and body 202 are aligned along the same longitudinal axis. As bestseen in FIGS. 33C and 33D, the pivoting head 208 has a second positionor transverse orientation, which is generally angled or transverse tothe body 202 of the anchor 200.

The head 208 may be actuated, for example, by turning threaded actuator210, such as a set screw, at the pedicle end 204 of the anchor 200. Asshown in FIG. 33B, the actuator 210 is positioned within the body 202and is configured to press against the proximal end of the first half212. As the actuator 210 pushes on the inner anchor half 212, the distalend of the first half 212 in turn pushes on the anchor head 208, therebycausing the head 208 to pivot about the pin 226. As shown in FIG. 33D,when the first half 212 is translated forward, the distal end of thefirst half 212 presses against a cam surface 228 on a portion of thehead 208. The head 208 pivots about the pin 226, thereby providing thehead 208 into the extended or deployed condition. Once the head 208fully pivots into place the actuator 210 also prevents movement of thehalves 212, 214 relative to each other, and thereby causes the anchor200 to increase in its bending stiffness.

Turning now to FIG. 34, a pedicle-based intradiscal fixation device oranchor 230 according to another embodiment is shown. The method offixation may be similar to the methods described herein for otherdevices. For example, the spine may be accessed posteriorly and thedevice 230 may be inserted into the pedicle 8 of the inferior vertebra6. The device 230 may be further advanced into the vertebral body 12 ofthe inferior vertebra 6. The device 230 may be positioned into thevertebral body 10 of the adjacent superior vertebra 4. Thus, the device230 may be incorporated into the inferior pedicle 8 which allows theanchor 230 to span from inferior to superior through the affected discspace 14.

Referring to FIG. 35, the pedicle-based intradiscal fixation device oranchor 230 is shown in more detail. The pedicle-based implant or anchor230 may include an inner core 232 extending from a first end or proximalend 234 to a second end or distal end 236, a segmented outer sheath 238positioned over the core 232, an optional proximal end cap 240 and adistal end cap 242 configured to secure the assembly, and a threadedcomponent or nut 244 configured to compress the segmented sheath 238.The inner core 232 may include an elongate body with a generallycylindrical shape or may be of another suitable shape orcross-dimension. The inner core 232 may be composed of an elastic orflexible material, such as Nitinol. In one embodiment, the body 202 ismade of a shape-memory material. For example, the core 232 may becomposed of a suitable biocompatible polymer, metal, alloy, or othersuitable material configured to impart shape memory. The inner core 232may have a generally curved or bent shape memory but is also able to betemporarily straightened or modified into a temporary shape.

The segmented outer sheath 238 may be the same or similar to thesegmented tubes 82 described herein. The segmented sheath 238 mayinclude a plurality of articulating members, linking segments, or links246. The plurality of links 246 may be arranged in a generally linearconfiguration or may be curved, for example, to mimic the shape of theinner core 232. The sheath 238 may be made from any suitable type ofbiocompatible material. The anchor 230 may include proximal end cap 240and distal end cap 242 to prevent the sheath 238 from disassembling fromthe inner core 232. The proximal end cap 240 may include a plurality ofouter threads or an outer threaded portion 248 configured to retain thenut 244. The nut 244 may have an inner threaded portion configured tomate with the outer threaded portion 248 of the cap 240. The nut 244 maybe threaded and moved forward distally to tighten the segmented sheath238 between the nut 244 and the distal cap 242.

As best seen in FIGS. 36A and 36B, the nut 244 is in a first positionwith a gap between the end of the nut 244 and the proximal end of thesegmented sheath 238. In the first unlocked position, the inner core 232and outer sheath 238 are permitted to straighten, for example, whenloaded inside the deployment tube 190 and/or curve freely into the shapememory of the inner core 232 when not constrained. As best seen in FIGS.36C and 36D, the nut 244 is advanced forward on the threaded portion 248of the cap 240 such that the nut 244 is moved to a second position. Inthe second locked position, the nut 244 presses against the proximal endof the outer sheath 238, thereby compressing the outer sheath 238,stiffening the links 246 of the outer sheath 238, and preventing theouter sheath 238 and the entire construct from unbending. In otherwords, the anchor 230 is locked in the curved or bent position shown andis unable to straighten.

In order to deploy the anchor 230, the anchor 230 may be first drawninto a deployment tube 190. Due to the super elasticity of the materialof the inner core 232 (e.g., Nitinol), the anchor 230 is configured tounbend and be held in the straight orientation inside the straightdeployment tube 190. After deployment from the tube 190, the core 232will resume its original curved or bent shape. After the core 232 hasbeen deployed, the segmented sheath 238 may be deployed over the core232. The mating surfaces of the linking segments 246 may have specificangled cuts that allowed the segments 246 to approximate the curve ofthe core 232 as the segments 246 are impacted over the core 232. In theembodiment shown, proximal cap 240 with outer threads 248 may beattached over the top of the core 230. Alternatively, the pedicle end234 of the core 232 may have the threads directly machined into the core232. In this configuration, the proximal cap 240 may be omitted. Thethreads 248 are configured to retain nut 244. When nut 244 is movedforward toward the distal end 236, the segmented sheath 238 iscompressed. This compression stiffens the anchor construct and preventsunbending. In another embodiment, the outer sheath 238 and inner core232 may be drawn and deployed together at the same time.

Turning now to FIG. 37, a pedicle-based intradiscal fixation device oranchor 250 according to another embodiment is shown. The method offixation may be similar to the methods described herein for otherdevices. For example, the spine may be accessed posteriorly and thedevice 250 may be inserted into the pedicle 8 of the inferior vertebra6. The device 250 may be further advanced into the vertebral body 12 ofthe inferior vertebra 6. The device 250 may be positioned into thevertebral body 10 of the adjacent superior vertebra 4. Thus, the device250 may be incorporated into the inferior pedicle 8 which allows theanchor 250 to span from inferior to superior through the affected discspace 14.

Referring to FIG. 38, the pedicle-based intradiscal fixation device oranchor 250 is shown in more detail. The pedicle-based implant or anchor250 may include an elongate body 252 extending from a first end orproximal end 254 to a second end or distal end 256. The elongate body252 may have a generally rectangular profile. Although the body 252 isshown to be rectangular in nature in this embodiment, it could alsoexist in uniquely different profiles as well. The body 252 may becomposed of an elastic or flexible material, such as Nitinol. The body252 may be composed of a suitable biocompatible polymer, metal, alloy,or other suitable material configured to impart shape memory. The body252 may have a generally curved or bent shape memory with the ability totemporarily change shape. The proximal end 254 of the body 252 mayinclude a threaded portion 258. The threaded portion 258 may beconfigured to engage an insertion instrument or other suitableinstrument. The distal end 256 may comprise a pointed tip, blunt tip, ormay be otherwise suitably configured to pierce and/or engage bone. Thesurfaces of the body 252 may be generally smooth to enhance insertionand/or may include teeth or other features to engage the bone.

In order to deploy the anchor 250, the anchor 250 may be first drawninto the deployment tube 190. Due to the super elasticity of thematerial of the body 252, the anchor 250 can unbend and be held in astraight orientation inside the deployment tube 190. During deploymentfrom the tube 190, the body 252 will resume its original bent or curvedshape. The ability of the anchor 250 to resume its original shape may bedue, for example, to the cross sectional area of the body 252 and/or thetype of shape-memory material.

Iatrogenic adjacent segment disease and other surgical issues have beenattributed to pedicle screw fixation previously. This intradiscalfixation devices and methods described herein may obviate the need forpedicle screw fixation while potentially avoiding their iatrogeniceffects. Traditional techniques may require multiple incisions for evenminimally invasive pedicle screw fixation. The pedicle-based intradiscalfixation devices described herein may provide better stability inflexion, extension, and/or axial rotation compared with other anchortype fixation methods used in the anterior or lateral approaches.Compared with an anterior/lateral anchor or screw and plate method, thepedicle-based intradiscal approach may be performed from a posteriorapproach, avoiding potential disruption of vasculature or nerve rootsfound in the anterior and/or lateral approaches.

It will be further understood that various changes in the details,materials, and arrangements of the parts which have been described andillustrated in order to explain the nature of this invention may be madeby those skilled in the art without departing from the scope of theinvention as expressed in the claims. One skilled in the art willappreciate that the embodiments discussed above are non-limiting. Itwill also be appreciated that one or more features of one embodiment maybe partially or fully incorporated into one or more other embodimentsdescribed herein.

What is claimed is:
 1. An implant for stabilizing an inferior vertebraand a superior vertebra, the implant comprising: a body extending from aproximal end to a distal end, a pivotable head connected to the distalend of the body, and an actuator for moving the pivotable head betweenan inline position and a transverse position, wherein the implant isconfigured to be inserted through a pedicle of the inferior vertebra andinto the superior vertebra, wherein the body is made of a shape-memorymaterial, and wherein the body has a curved shape-memory orientation anda temporarily straight orientation.
 2. The implant of claim 1, whereinthe body includes a first half and a second half.
 3. The implant ofclaim 2, wherein the first and second halves are permitted to slideindependent of one another.
 4. The implant of claim 3, wherein the firsthalf includes one or more male portions and the second half includes oneor more female portions configured to receive the one or more maleportions of the first half.
 5. The implant of claim 4, wherein the maleportion includes a first set of two opposed projections extending awayfrom one another and configured to fit within a first set of twocorresponding opposed recesses in the second half, and the second halfincludes a second set of two opposed projections extending toward oneanother and configured to fit within a second set of two correspondingopposed recesses within the male portion of the first half.
 6. Theimplant of claim 2, wherein when the actuator presses against the firsthalf of the body, the opposite end of the first half in turn pushes onthe pivotable head, thereby causing the head to pivot.
 7. The implant ofclaim 6, wherein once the head fully pivots into the transverseposition, the actuator prevents movement of the first and second halvesrelative to each other, thereby causing the body to increase instiffness.
 8. The implant of claim 1, wherein the actuator is a setscrew.
 9. A method for stabilizing an inferior vertebra and a superiorvertebra, the method comprising: posteriorly accessing a spine of apatient; inserting an implant into a pedicle of the inferior vertebra,the implant having a body having a first half and a second half slidablerelative to one another, a pivotable head connected to the body, and anactuator configured to move the pivotable head, wherein the implant isinserted with the pivotable head in an inline orientation; inserting theimplant into a vertebral body of the inferior vertebra; inserting theimplant into a vertebral body of the superior vertebra, wherein theimplant traverses a disc or disc space between the inferior and superiorvertebrae; and moving the pivotable head to a transverse orientation,thereby fixating the inferior and superior vertebrae.
 10. The method ofclaim 9, wherein the body is composed of a shape-memory material. 11.The method of claim 10 further comprising drawing the implant into astraight deployment tube such that the body is straightened within thetube, and deploying the implant from the deployment tube, wherein thebody returns to a curved shape.
 12. The method of claim 9, whereinmoving the pivotable head includes actuating the actuator such that theactuator presses against the first half of the body and the first halfin turn pushes on the pivotable head, thereby causing the head to pivot.13. The method of claim 12, wherein once the head fully pivots into thetransverse orientation, the actuator prevents movement of the first andsecond halves relative to each other, thereby causing the body toincrease in stiffness.